Add sub-phases and sub-milestones Merged

We really like how we can add features to phases and then on the gantt chart you can expand the phaase and see the featues as well as collapse to hide them. We would like this same functionality with phases and milestones. For example, I could have a marketing phase with linked phases and milestones. I want to be able to expand the marketing phase to see the details or collapse it to hide them.